The invention relates to a method of firing ceramic materials, such as tiles and the like, and to a kiln for its implementation.
Such a method is designed for adoption wherever one has a manufacturing process in which ceramic materials, for example ceramic tiles, are conveyed along a predetermined path each stage or zone of which is characterized during operation at regular tempo by the existence of a given temperature level, and it is the collective shape of the various levels that determines the firing cycle.
In conventional firing cycles, as implemented currently in continuous roller kilns, the ceramic material is fired while running through the kiln from end to end. With operation at regular tempo, a precise distribution of temperatues is produced along the longitudinal axis of the kiln; this effect is conventionally termed the "firing curve", a curve which, in practice, represents the entire thermal cycle to which the material put through the kiln is subjected. In conventional kilns, where progress of the material is continuous and uniform, tiles are conveyed steadily through zones held at different temperatures; accordingly, the thermal gradient to which a given type of tile can be subjected without any kind of difficulty occurring will depend, travel speed apart, substantially upon the charactistics of the firing curve--i.e. its steepness, or the degree and duration of the steps it exhibits. A situation such as this imposes a physical limitation that can not be removed, inasmuch as the chosen travel speed dictates that the positive or negative slope of the curve cannot go beyond certain values--more exactly, values beyond which the temperature gradient induced in the material will be such as to inhibit faultless implemention of the process, or worse, to cause damage to the material. The result is that one has a minimum time limit below which the duration of the firing cycle as a whole cannot be allowed to drop.
Accordingly, the object of the invention is to overcome the limitation described above, and speed up the firing cycle.